<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		#a p{
			background-color: red;
		}
		.w p{
			color:blue;
			text-indent: 2em;
			
		}
	</style>
</head>
<body>
	<div id="a" class="w">
		<p>qqq</p>
		<p>www</p>
	</div>
</body>
</html>